1. Field of the Invention
The invention relates to a device for sensing aural data.
2. Description of the Prior Art
Extensive investigation has already been done in obtaining qualitative, more particularly also quantitive, data relevant to the condition of normal and disturbed hearing, the discovery made by Kemp (see EP-B1.15258) being particularly of significance in this respect that sound emissions in the external canal can be measured as a reaction to a sound event which are indicative of the condition in the ear. These so-called evoked otoacoustic emissions were measured by Kemp with the aid of an acoustic sensor comprising a highly-sensitive miniature microphone and a sound emitter. It is also known that otoacoustic emissions may also materialize spontaneously, i.e. without the ear being stimulated from without.
Direct ear-drum vibration measurement in examining the mechanics of the middle ear is already being done by the method of laser Doppler vibrometry. This method is described in the German publication of N. Stasche, H. -J. Foth and K. Hormann in HNO (1993), 41, pages 1 to 6. In this method the beam of a He--Ne laser is split by a beam divider and the two component beams, one of which is directed at the object being examined, are subsequently caused to produce an interference effect. From the shift in frequency the amplitude of the sensed point in the ear-drum is determined. For inputting the laser light to the object being examined Stasche et al make use of a flexible fiber optic lightguide which needs to be located in the immediate vicinity of this object. Apart from problems as to resolution (small aperture) this may also make measuring difficult on the patient since the fiber optic lightguide must not come into contact with the ear-drum.